CA2224081A1 - Method and apparatus for preparing purified terephthalic acid - Google Patents
Method and apparatus for preparing purified terephthalic acid Download PDFInfo
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- CA2224081A1 CA2224081A1 CA002224081A CA2224081A CA2224081A1 CA 2224081 A1 CA2224081 A1 CA 2224081A1 CA 002224081 A CA002224081 A CA 002224081A CA 2224081 A CA2224081 A CA 2224081A CA 2224081 A1 CA2224081 A1 CA 2224081A1
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- terephthalic acid
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- purified terephthalic
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C63/00—Compounds having carboxyl groups bound to a carbon atoms of six-membered aromatic rings
- C07C63/14—Monocyclic dicarboxylic acids
- C07C63/15—Monocyclic dicarboxylic acids all carboxyl groups bound to carbon atoms of the six-membered aromatic ring
- C07C63/26—1,4 - Benzenedicarboxylic acid
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
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Abstract
A method and apparatus for purifying crude terephthalic acid from a liquid dispersion thereof also containing impurities selected from unreacted starting materials, solvents, products of side reactions and/or other undesired materials is provided. The method comprises the steps of filtering the dispersion to form a crude terephthalic acid filter cake (F-1), dissolving the filter cake in a selective crystallization solvent at an elevated temperature to form a solution (T-3, T-4), crystallizing purified terephthalic acid from the solution in the crystallization solvent by reducing the temperature of the solution (S-1), and separating the crystallized purified terephthalic acid from the solution (F-2). According to the invention, the selective crystallization solvent is non-aqueous, non-corrosive and essentially non-reactive with terephthalic acid. Preferably, the selective crystallization solvent is N-methyl pyrrolidone. The method and apparatus produces purified terephthalic acid having a purity desired for use in forming polyester resin and other products at an economically attractive rate and at operating conditions of reduced severity which require a lower capital investement and simplified processing.
Description
W O96/40612 PcT/u',51~9C
METHOD AND APPARATUS FOR PREPARING
PURIEIED TEI~;l ~ lALIC ACID
S The present invention relates to a method and a~aldtus for prcp~illg ,.... ;r;r~ terephth~lic acid. It also relates to m~thn lc and ap~-.dll~ses for ~uliryhlg crude t~lcp}~ ir acid to produce a purified tere~hth~lir acid product which is auseful starting m~t~ri~1 for p.~lu.;il~g polyester resin, w_ich is in turn useful for the pro-11lctinn of fibers, f~, plastic bottles, and polyester resin structures, often 10 rc;-lrolced by other m~trrialc such as glass fiber.
BACKGROUND OF THI~ INVENTION
Purified terephth~lir acid (PTA) is a starting m~teri~l for the formation of polyester resin, w_ich is, in turn, used to make many materials of co.. ~-;e having a variety of utilities. Purified terephth~lir acid is formed from Ucrude" terephth~lic acid cGuv~ m~lly by a llul lbel of pllrifir~tion m~th~c, often with the aid of catalysts. The " .- Il ~~c for ~uliry ..lg crude lclc~hll~lir acid helclofc lc available are not completely ic~ticf~ctory either from an eng;..r~ g s~d~oil~L, or from an c~n~ .;r ~l~l~ill~, yet the purity of the purified terepht_alic acid is an important ~ t~ .. ;.-~.. 1 of the s~ticfa~ il,ess of the processes by w_ich the polyester resin is formed.
A number of reaction systems are known for forming crude terephth~lir acid from a variety of starting m~teri~lC. The ~ ;rir;~lion aspects of the present invention may be used with s~1bst~nti~11y any of these reaction systems, but in 25 accordance with the invention it is ylef~ d that a reaction system involving the oxi~l~fion of paraxylene (p-xylene) be employed, and the use of such a syllll~sis system forms a part of the present invention.
The problems of ~icl;.,~ and prior systems for pro~h1ri~ ~ulir~cd ~le~hl1lA1ir acid center around the tliffir111ties in mnning the reaction systems to 30 produce good yields of crude terephthA1ir acid eco~--....irA11y, compounded by the ~iffit~111tiPS of refining the crude terephthalic acid to e1;...;.~Atf~ illl~ulilies and ull~ ~d co.--pollel.~ to produce ~u ;l-ed terephth~lir acid of a quality suitable as a starting m~tPri~l for producing polyester. CO.lco-..i~.L problems in prior systems include the _igh capital ill~ LIll.,.ll required for PTA plants, the severity of u~ldLillg co~ of prior p ~~s, both for the p~lu~;lion of crude ~l~hlh~lir acid, and 5 for its ~--, ;r. ,.lion, and the need for h~ntlling catalyst systems and reaction solvents, as well as reaction byproducts in a way such that envirl nmPnt~l problems are ...;..;.I.;~d, and loss of material is also controlled.
SUMMARY OF THE INVENTION
In acco--lallce with the present invention there is provided a method and apparatus for producing purified terephth~lir acid. In one aspect, the method h -flec the ~ n of crude ~,~ lir acid by the 07~ tion of p-xylene. The oxir~tin step ~.u.lu~;es not only ~l~ lir acid, but by side reactions p-toluic acid and 4-carbo~yl,c~ hyde (4-CBA). The product produced in the oxidation step is a liquid ~lisp~rsion cr,nt~ininp: u~iac~d starting m~t~ri~l~, solvents, if any have been used, the products of side reactions, particularly those just mentioned, and other m~t~ri~l~ which are not desired in the sought-for purified terephthalic acid.
The oxidation step of the present invention is so con~ rted that the co.l~el~ion to crude ~,~ .Ih~lir acid should be at least about 30% by weight per pass of p-xylene.
In further a~.da,-ee with the invention, the crude terephth~lir acid from the ~idi~, is first grossly se,p~ rfl from the other m~tori~lc from the oxidi_er and then it is re-dissolved in a sele~,liv~ cryst~lli7~tion solvent and, optionally, one or more additional solvents of the invention ~ d below. I~e re-dissolved crude ~l~l.ll.~lir acid is then cryst~lli7rd out of the selective cryst~lli7~tion solvent and ~lrl~litir,n~l solvents of the i~ ,lliu~- in one or, preferably, two cryst~lli7~tion stages.
Provision is made to s~le out the cryst~lli7~od and pro~ ,ly purified Ltlc~lh~lir acid from the solvents of the invention, and the filter cake of purified L,e~ lir acid llltim~t~ly obt~in~ is washed with other solvents of the inventionand llltim~t.oly dried for storage or for fur~er proc~ccin~.
The i~ vc:llLioll also c~ pl l~s that steps are ;.. ~ d~l to reclaim and recycle the solvents of the invention at each stage of cryst~lli7~tion and w~lling, inr~ in~
W 096/40612 PCT/U~GI~SOI~
"j ;
recycle of some of the recovered mAtPriAl~ to the o~ci~li7~r. Steps are also taken to closely control the delivery of any objectionable materials to the en~dlon,nellL.
In an ~~ ulL~lL aspect, the present invention is based on several discoveries relating to solvents w_ich are ~rÇ~Iive to bring about t_e ~ulirlcaLion of crude5 t~ lir acid through cryst~l1i7~tinn and sep~r~tinn steps. These discoveries may be ~.. .~. ;~ cl in several ways as follows.
The selective cryst~l1i7~tion solvents useful in the Pr~Ct;re of the present invention include those in w_ich (a) the ;~ Ps desired to be sep~dted from terephth~1ir. acid to purify it are l_laLi~,ely more soluble in the solvent than is the~0 terepht_alic acid at sllbst~ntiA11y every te-.-l.c~ --.e within t_e desired range of ,s at which the solvent contAinin~ terephthA1ir acid is to be h~n~l1ed, and (b) the t~ Jh~ lit' acid is more soluble at an elevated Lc~ )eldLul~ and less soluble at a lower or l~luced ~ . It is to be ~ ood that the term "seleiLi~e cryst~lli7~tion solvent" is intPnrl~cl to mean solvents useful in the selective 1~ crystAl1i7Ation of t~ 1ir- acid as described above and as described in greater detail below and as shown in FIG. 2.
In this c~"".~il;rJn it should be noted that U.S. Patent No. 3,465,035 m~nti(~nethat certain organic solvents (~li~ine, dhlleLllyl sufoxides, dimethyl foramide, and the like) have been used to purify ~l~ ir acid, but that they suffer from being unstable 20 in air and easily form A~rliticm products with L,~ 1ir acid. This same patent, alollg with several others, also teaches the use of acetic acid and water as purification solvents for 1CI~ hI1~A1;C acid. By ~I~LlasL~ the selective crystAlli7AfiQn solverlts accolding to the present invention are (a) non-Aqueo~le (b) non-corrosive, and (c) ny non-reactive with ~ .11.Alir acid and do not include those prior practices 25 just described. SperifirAlly, wster, acetic (and other slkyl) acid, snd the above-mentioned organic solvents are ~clllded from the selective crystAlli~Afion solvents which are CO~ P1Ated by the present invention.
In accol~ce with the invention, the ~ f~ d selecti~re crystAl1i7Atil)n solvent is N-methyl pyrrolidone (NMP), for the several reasons ~liccllccyl below, and for its superior pclr .. ~I-re.
W096/40612 PCTAU~5~ 015 N-methyl pyrrolidone (NMP) is the most p1cfe,~d selective cryst~lli7~ti~n solvent for the ~31aClicC of the invention. It is non-aqueous, thPnnAIly stable, non-toxic (c.~vilo.~.nP-.Ii lly safe), non-co1.c3sivc, and cc3",-l,c.c,ally available. NMP is the p1cfc11cd selective crystAlli7Afion solvent for the p1aCLice of the present S il~ 311, because its solubility versus ~ ..,e curve for Ic1~3hll.~lir acid slopes upwardly and to the right, which means that terephthalic acid can be dissolved in it at elevated h,~ alu1cS, and ~31c~ a~d or cryst~lli7~o-d from it at lower t~ 1l1~3tlaLulcS.
,Alth.~llgh NMP is the most p1~.1~1 selective cryst~lli7~tir3n solvent, it is tobe understood that, in accordance with the present h1~11Lioll, other ~31cfeLl~d selective crystAlli7Atio~ solvents for ~ -. ;r~r,.lion of crude ~,~13hll.~1ir acid can be selected from various polar organic solven~s inr~ i~, but not intentl~d to be limited to, N-aL~cyl-2-pyrrolidone (such as N-ethyl pyrrolidone), N-ll.e.c~1-Lo~lkyl-2-pyrrolidone (such as N-ll~e~ .yl-2-pyrrolidone), N-aLkyl-2-thiopyrrolidone 15 (such as N-methyl-2-thiopyrrolidone), and N-hyd1~,~yalkyl-2-pyrrolidone (such as N-hydroxyethyl-2-pyrrolidone), and the like, and mixtures thereof. Still other selective cryst~lli7~tion solvents col,~."l,lated by the present invention include, but are not intPn~P~l to be limited to, sulfolane, methyl sulfolane, the sulfones, the morpholines (such as, morpholine and N-formyl morpholine), the carbitols, Cl to 20 c'2 alcohols, the ethers, the amines, the amides, and the esters, and the like, and ules thereof.
It is p1cL~lcd that the desired sele~live cryst~lli7~tion solvent be used in a multi-stage cryst~lli7Ation process in c~ alion with one or more additional solvents, preferably two such additional solvents, particularly where the crude 25 t~ lir acid is less than about 98% pure. Preferably, a wash solvent, such as, but not intended to be limited to, p-xylene, acetone, methyl ethyl ketone (MEK) or An~1~ and the like, is used in the W~iLg of the initial filter cake obtained from the first separation of crude terephthalic acid from other m~tPri~l~ issuing from the oxi-li7.r.r. In Arl-liti~rl, a displ~rc .~P-.I solvent having a low boiling point, such as, 30 but not intPn-1e(1 to be limited to, ..~ 1, acetone, MEK, and the like, may be used. Preferably".~ 1, is used as the displAreTnPnt solvent in association with -W O96/40612 PCT~US96/09OlS
the third filter following the second cryst~lli7~tion stage in the l"er~ cd process.
The desired ~ solvent ~ pl~reS the selective crysf~lli7~tion solvent fromthe resllltin~ filter cake, whcl~y ~ lly only the displ~rPmPnt solvent is present during the drying process. It is to be lmt1~Pr~tQod that the low boiling point S of the displ~rPmP-nt solvent f~Cilit~tps the drying of the filter cake.
As dc~,clil)ed above, NMP is the most y~,f~lcd selective cryst~lli7~tion solvent for the pr~tire of the invention. It is non-aqueous, fh.orm~lly stable, non-toxic (~ ilu~ lly safe), non-col,osi~, and co--...-~r~ially available. NMP is the prcf~,lcd selective cryst~lli7~tion solvent for the practice of the present 10 ..,~io~, bec~llcP, among other things, its solubility versus ~ pe~n~ c curve for terepht_alic acid slo~es upwardly and to the right, which means that t~ hLllalicacid can be dissolved in it at elevated Ir~ es, and p-~c;~ ed or cryst~lli7f~d from it at lower Ir~ .,;,. However, the solubility versus t~ ldLu~t cuNe forterephthalic acid is of a much milder slope than the solubility cuNes in NMP for15 other m~teri~lC sought to be s~m~o~r~ from crude terephthalic acid, such as benzoic acid, 4~bu~ nl~l~yde (4-CBA), and p-toluic acid. As a co~e~lucllce, when crude tel~ll.~lir acid, cont~inin~ or associa~d with unreacted startin~g m~trri~lc, solvents (if any), and plOlUCl:i of side re~tion~, such as those m~ntionr~l above, or other undesired m~tPri~lc, is dissolved in NMP at an elevated lellll~Cldlu~, 20 ~ y all the m~t~ori~lc are dissolved or at least highly r~ cl~e(l. Then upon removal of heat and cooling of the NMP soh~tion of such dissolved m~teri~l.c, the pure terephth~lir acid plef,l. ~lially CNst~lli7Ps out, while the other more soluble m~teri~lc which may be .~,~.lcd as ;~ s for the present purposes remain in solution in NMP. A sep~ration is thus effected bcl~ purified terephthalic acid 25 and its ~C~oc~ d ;~..p~;l;es. NMP may be stripped of the i,--~-ilies in a lcc1~;"-;"~ column and recycled into the process, while the i~u-ilies may be recycled to the oxirli7~r step or olL~ c dis~osed of.
From the fu~oillg, it can be seen that in acco-~ ce with one aspect of the present invention, a method is provided for pro~ rin~ pl~rifiP~l terephth~lir acid 30 from crude t~.~.~lh~lir acid in which the crude tel~?l.lh~lic acid is dissolved in a desired cryst~lli7~tion solvent at an elevated ~ to form a solution and -CA 0222408l l997-l2-08 further, in which a l,ulirled tClc~hllizilic acid is crystz~lli7~d from that solution at a reduced tc.ll~cldLulc.
In acccldal~ with another aspect of the invention, a method and a~alatus are provided for ~uliryillg crude terephthz~lir acid from a liquid dispersion thereof 5 also cu,.li.i..i..g unreacted starting mz.trriz.l~, solvents, products of side rez~rtion~, and/or other ul~h~,d mz.t~riz~l~ in which the crude ~~ hll.~lir acid is filtered from that n~i~r~ion to partially sepz~. ale it from the other materials contained therein by filtration to produce a crude ~~ hlhz~lir acid filter cake, and then dissolving that filter cake in a desired selective crystz~lli7z~tio} solvent at an elevated t~ dl...c to form a solution. Purified terephthz~lir, acid is crystz~lli7~d from that solution by reducing the If ..l,~-dt-.lre thereof and is s~ala~cd from the solvent followingcrystz.lli7~.tion In accoldd.-ce with still another aspect of the invention, a method and a~palaLus are provided for producing purified terephthz.lic acid from crude 15 terephthalic acid by dissolving the crude tcrephll.,.lir acid in a desired selective crystz~lli7z~ti~n solvent at an Cl.,vaLcd t~ f ~l---c to form a first solution. First stage purified ltlc~hLLalic acid is crystz-lli7~d from that first solution at a reduced '...e. I'he first stage pllrifi~d terephthalic acid is se~alàLed from the solvent solution of other i~ ulilies and redissolved in the desired selective crystz.lli7z.tion 20 solvent at an elevated Iclll~."alwc to form a second solution. This second solution is cryst~lli7rA at a reduced trmrrrat~lre to for n a second stage purified terephthz,lir acid and the second stage purified lclc~;ll.~lir, acid is ~_~alaLed from the second solution.
In accoldallcc with yet another aspect of the invention, crude terephthalic 25 acid is synth~o~i7~d by contzlrting paraxylene with oxygen in an oxidi_er reaction.
The crude terephthz~lir acid is withdrawn from the oxidi_er and seL,aldlcd grossly from the side products of the reaction, and unreacted starting mztrriz~l~ The separated crude lc~h~ lir acid is then dissolved in a desired selective crys~lli7~tit~n solvent at an elevated lclll~elalule and cryst~lli7ed from it as purified 30 t~hfh~lir acid at a reduced l~ )c~alwc. More than one stage of dissolving in a desired sclc~;livc cry.st~lli7~tion solvent at an cl~,val~d ~ ...t followed by W O 96/40612 PCT~U~ S~15 crystAlli7~tion at a reduced 1' ~ C;t with accol~dllyillg separation and washing of the cryst~lli7~ purified ~,~hll.~lir acid, may be ~.,Lr~,lmed.
~ From the r lCgOillg, it can be seen that an object of the present invention to provide an il~ vcd method and a~alatus for producing purified ~rt,~h~ lir acid S of a purity desired for use in f~ g polyester resin and other products, at an -";~ ly aLLld~;livc rate, and at OlJelalillg cQr~Aition~ of reduced S~ ,iLy which require a lower capitdl i l~ LIt and simplified yr~ces~illg. The manner in whichthese and other objects of the i lve~l~ll are attained may be learned by co~ eration of the det,i~ de..~ ion of the invention which follows, together with the 10 ~CCol..~ yi~g dl~wi~g~.
BRIEF DESCRIPI ION OF I~IE DRAVVINGS
A more complete l~n~ uliuf~ of the method and a~dldlus of the present ,n may be ollt~i,led by l~fe..,.lce to the following Detailed Description when 15 taken in cQl.j.~ l;on with the accom~-ying Dl~whlgs wl.~,c ,1:
PIGS. lA and lB are simplified flow diagrams of an a~dlalus with which the method according to the invention may be practiced wlltlcllLFIG~ lA is that portion of the a~dlalUS for pc~Çc"l.Piug the first stage crystAlli7~tiQn steps and wLelein FIG. lB is that portion of the a~ .lus for pclr(.lll.i-.g the second stage 20 cryst~lli7~ti~-n steps; and FIG. 2 is a plot of solubility versus t~ ,ldlul~i curves for ~,hlLalic acid and for hll~ulilies or side reaction products commonly ~oci~te~i with crude tere~hth~lir acid.
DETAILED DESCRIPTION OF EMBODIMENTS
nPc~
The present invention relates to the development of a new PTA
".~..,.r~ ",;,~ t~hnology. Colll~alcd to the current widely used PTA technology,this technology provides a ~I,sli~ y lower capital hl~lcsL~cnl in new PTA plant 30 co~llu.;lion, as well as lower costs of plant C~lldtiOIl. It also provides means for W 096/40612 PCTA~ 9015 current DMT plants to co-~luce PTA, to sl~ their co.. l.eiil i ~c~ess against newer PTA plants.
Process S.. ~, y The success of this process is based on the development of a low ~ ,Swc, low l~ll~ClaLul~, non-aqueous, highly sel~;livc crystAlli7Ation technology. The cryst~lli7Ation ~'h~-hlhyy can purify the crude tcL~lJt-.lt.Alir acid (TA) with purity as low as from ~ ,. ~n about 70% (from the oxi~ii7~or) and about 98 + % in the first-stage crystallizer, and about 99.99+ % in the second-stage crystallizer. This allows the TA ~xi(1j7~r to be O~llatcd at much lower s~ ily than those of widely used prior art ~uc~s. No acetic acid (as solvent/diluent) or l,lo~h¢-catalyst illiLialo~
is needed in the oxi~li7~r in acccl~ ce with the present invention. The selective cryst~lli7Ation solvent used in the cryst~lli7~tion process is non-aqueous, thP~ lly stable, non-toxic (e~lvi~u~ lly safe), non~,,usivc~ and co~ ;ially available.
When c~lyil-g out the method accc,~ g to the present invention with the apparatus shown in FIGS. lA and lB, c~ layillg NMP as the selective cryst~lli7~tion solvent, the present inventors have d~ I n~ aled TPA purity levels of up to 99.9+wt%
after a first cry.ct~lli7~tion process, and up to 99.99+wt% after a second cry.st~lli7~ti~ n process. In ~ liculdl~ Table 1 illustrates the recovery of 99.95wt% pure TPA after the first cryst~lli7-~tiQn process and 99.997wt% pure TPA after the second cry~t~lli7~tinn process, from crude TPA (89.89wt% TPA).
-W O96/40612 PCTrU~C~S01 TARTF l 1st Cry.~t~11i7~tion ~nf1C~i.ll.,i1l;l.
S
(a) Weight of TPA: 56.34 grams 31.81 grams (b) Weight of Cryst~lli7~tiQn Solvent: 400.02 grams 248.38 grams (c) Saturation Te.~ lule: 60~C
(d) Cryst~lli7~tiorl Tell~p~,laLIlre: 15~C (one hour) (1) Crude TPA Product Composition:
Benzoic p-Toluic 4-CBA TPA Others 0.39wt% 4.49wt% 2.49WT% 89.89WT% 2.74VVI%
METHOD AND APPARATUS FOR PREPARING
PURIEIED TEI~;l ~ lALIC ACID
S The present invention relates to a method and a~aldtus for prcp~illg ,.... ;r;r~ terephth~lic acid. It also relates to m~thn lc and ap~-.dll~ses for ~uliryhlg crude t~lcp}~ ir acid to produce a purified tere~hth~lir acid product which is auseful starting m~t~ri~1 for p.~lu.;il~g polyester resin, w_ich is in turn useful for the pro-11lctinn of fibers, f~, plastic bottles, and polyester resin structures, often 10 rc;-lrolced by other m~trrialc such as glass fiber.
BACKGROUND OF THI~ INVENTION
Purified terephth~lir acid (PTA) is a starting m~teri~l for the formation of polyester resin, w_ich is, in turn, used to make many materials of co.. ~-;e having a variety of utilities. Purified terephth~lir acid is formed from Ucrude" terephth~lic acid cGuv~ m~lly by a llul lbel of pllrifir~tion m~th~c, often with the aid of catalysts. The " .- Il ~~c for ~uliry ..lg crude lclc~hll~lir acid helclofc lc available are not completely ic~ticf~ctory either from an eng;..r~ g s~d~oil~L, or from an c~n~ .;r ~l~l~ill~, yet the purity of the purified terepht_alic acid is an important ~ t~ .. ;.-~.. 1 of the s~ticfa~ il,ess of the processes by w_ich the polyester resin is formed.
A number of reaction systems are known for forming crude terephth~lir acid from a variety of starting m~teri~lC. The ~ ;rir;~lion aspects of the present invention may be used with s~1bst~nti~11y any of these reaction systems, but in 25 accordance with the invention it is ylef~ d that a reaction system involving the oxi~l~fion of paraxylene (p-xylene) be employed, and the use of such a syllll~sis system forms a part of the present invention.
The problems of ~icl;.,~ and prior systems for pro~h1ri~ ~ulir~cd ~le~hl1lA1ir acid center around the tliffir111ties in mnning the reaction systems to 30 produce good yields of crude terephthA1ir acid eco~--....irA11y, compounded by the ~iffit~111tiPS of refining the crude terephthalic acid to e1;...;.~Atf~ illl~ulilies and ull~ ~d co.--pollel.~ to produce ~u ;l-ed terephth~lir acid of a quality suitable as a starting m~tPri~l for producing polyester. CO.lco-..i~.L problems in prior systems include the _igh capital ill~ LIll.,.ll required for PTA plants, the severity of u~ldLillg co~ of prior p ~~s, both for the p~lu~;lion of crude ~l~hlh~lir acid, and 5 for its ~--, ;r. ,.lion, and the need for h~ntlling catalyst systems and reaction solvents, as well as reaction byproducts in a way such that envirl nmPnt~l problems are ...;..;.I.;~d, and loss of material is also controlled.
SUMMARY OF THE INVENTION
In acco--lallce with the present invention there is provided a method and apparatus for producing purified terephth~lir acid. In one aspect, the method h -flec the ~ n of crude ~,~ lir acid by the 07~ tion of p-xylene. The oxir~tin step ~.u.lu~;es not only ~l~ lir acid, but by side reactions p-toluic acid and 4-carbo~yl,c~ hyde (4-CBA). The product produced in the oxidation step is a liquid ~lisp~rsion cr,nt~ininp: u~iac~d starting m~t~ri~l~, solvents, if any have been used, the products of side reactions, particularly those just mentioned, and other m~t~ri~l~ which are not desired in the sought-for purified terephthalic acid.
The oxidation step of the present invention is so con~ rted that the co.l~el~ion to crude ~,~ .Ih~lir acid should be at least about 30% by weight per pass of p-xylene.
In further a~.da,-ee with the invention, the crude terephth~lir acid from the ~idi~, is first grossly se,p~ rfl from the other m~tori~lc from the oxidi_er and then it is re-dissolved in a sele~,liv~ cryst~lli7~tion solvent and, optionally, one or more additional solvents of the invention ~ d below. I~e re-dissolved crude ~l~l.ll.~lir acid is then cryst~lli7rd out of the selective cryst~lli7~tion solvent and ~lrl~litir,n~l solvents of the i~ ,lliu~- in one or, preferably, two cryst~lli7~tion stages.
Provision is made to s~le out the cryst~lli7~od and pro~ ,ly purified Ltlc~lh~lir acid from the solvents of the invention, and the filter cake of purified L,e~ lir acid llltim~t~ly obt~in~ is washed with other solvents of the inventionand llltim~t.oly dried for storage or for fur~er proc~ccin~.
The i~ vc:llLioll also c~ pl l~s that steps are ;.. ~ d~l to reclaim and recycle the solvents of the invention at each stage of cryst~lli7~tion and w~lling, inr~ in~
W 096/40612 PCT/U~GI~SOI~
"j ;
recycle of some of the recovered mAtPriAl~ to the o~ci~li7~r. Steps are also taken to closely control the delivery of any objectionable materials to the en~dlon,nellL.
In an ~~ ulL~lL aspect, the present invention is based on several discoveries relating to solvents w_ich are ~rÇ~Iive to bring about t_e ~ulirlcaLion of crude5 t~ lir acid through cryst~l1i7~tinn and sep~r~tinn steps. These discoveries may be ~.. .~. ;~ cl in several ways as follows.
The selective cryst~l1i7~tion solvents useful in the Pr~Ct;re of the present invention include those in w_ich (a) the ;~ Ps desired to be sep~dted from terephth~1ir. acid to purify it are l_laLi~,ely more soluble in the solvent than is the~0 terepht_alic acid at sllbst~ntiA11y every te-.-l.c~ --.e within t_e desired range of ,s at which the solvent contAinin~ terephthA1ir acid is to be h~n~l1ed, and (b) the t~ Jh~ lit' acid is more soluble at an elevated Lc~ )eldLul~ and less soluble at a lower or l~luced ~ . It is to be ~ ood that the term "seleiLi~e cryst~lli7~tion solvent" is intPnrl~cl to mean solvents useful in the selective 1~ crystAl1i7Ation of t~ 1ir- acid as described above and as described in greater detail below and as shown in FIG. 2.
In this c~"".~il;rJn it should be noted that U.S. Patent No. 3,465,035 m~nti(~nethat certain organic solvents (~li~ine, dhlleLllyl sufoxides, dimethyl foramide, and the like) have been used to purify ~l~ ir acid, but that they suffer from being unstable 20 in air and easily form A~rliticm products with L,~ 1ir acid. This same patent, alollg with several others, also teaches the use of acetic acid and water as purification solvents for 1CI~ hI1~A1;C acid. By ~I~LlasL~ the selective crystAlli7AfiQn solverlts accolding to the present invention are (a) non-Aqueo~le (b) non-corrosive, and (c) ny non-reactive with ~ .11.Alir acid and do not include those prior practices 25 just described. SperifirAlly, wster, acetic (and other slkyl) acid, snd the above-mentioned organic solvents are ~clllded from the selective crystAlli~Afion solvents which are CO~ P1Ated by the present invention.
In accol~ce with the invention, the ~ f~ d selecti~re crystAl1i7Atil)n solvent is N-methyl pyrrolidone (NMP), for the several reasons ~liccllccyl below, and for its superior pclr .. ~I-re.
W096/40612 PCTAU~5~ 015 N-methyl pyrrolidone (NMP) is the most p1cfe,~d selective cryst~lli7~ti~n solvent for the ~31aClicC of the invention. It is non-aqueous, thPnnAIly stable, non-toxic (c.~vilo.~.nP-.Ii lly safe), non-co1.c3sivc, and cc3",-l,c.c,ally available. NMP is the p1cfc11cd selective crystAlli7Afion solvent for the p1aCLice of the present S il~ 311, because its solubility versus ~ ..,e curve for Ic1~3hll.~lir acid slopes upwardly and to the right, which means that terephthalic acid can be dissolved in it at elevated h,~ alu1cS, and ~31c~ a~d or cryst~lli7~o-d from it at lower t~ 1l1~3tlaLulcS.
,Alth.~llgh NMP is the most p1~.1~1 selective cryst~lli7~tir3n solvent, it is tobe understood that, in accordance with the present h1~11Lioll, other ~31cfeLl~d selective crystAlli7Atio~ solvents for ~ -. ;r~r,.lion of crude ~,~13hll.~1ir acid can be selected from various polar organic solven~s inr~ i~, but not intentl~d to be limited to, N-aL~cyl-2-pyrrolidone (such as N-ethyl pyrrolidone), N-ll.e.c~1-Lo~lkyl-2-pyrrolidone (such as N-ll~e~ .yl-2-pyrrolidone), N-aLkyl-2-thiopyrrolidone 15 (such as N-methyl-2-thiopyrrolidone), and N-hyd1~,~yalkyl-2-pyrrolidone (such as N-hydroxyethyl-2-pyrrolidone), and the like, and mixtures thereof. Still other selective cryst~lli7~tion solvents col,~."l,lated by the present invention include, but are not intPn~P~l to be limited to, sulfolane, methyl sulfolane, the sulfones, the morpholines (such as, morpholine and N-formyl morpholine), the carbitols, Cl to 20 c'2 alcohols, the ethers, the amines, the amides, and the esters, and the like, and ules thereof.
It is p1cL~lcd that the desired sele~live cryst~lli7~tion solvent be used in a multi-stage cryst~lli7Ation process in c~ alion with one or more additional solvents, preferably two such additional solvents, particularly where the crude 25 t~ lir acid is less than about 98% pure. Preferably, a wash solvent, such as, but not intended to be limited to, p-xylene, acetone, methyl ethyl ketone (MEK) or An~1~ and the like, is used in the W~iLg of the initial filter cake obtained from the first separation of crude terephthalic acid from other m~tPri~l~ issuing from the oxi-li7.r.r. In Arl-liti~rl, a displ~rc .~P-.I solvent having a low boiling point, such as, 30 but not intPn-1e(1 to be limited to, ..~ 1, acetone, MEK, and the like, may be used. Preferably".~ 1, is used as the displAreTnPnt solvent in association with -W O96/40612 PCT~US96/09OlS
the third filter following the second cryst~lli7~tion stage in the l"er~ cd process.
The desired ~ solvent ~ pl~reS the selective crysf~lli7~tion solvent fromthe resllltin~ filter cake, whcl~y ~ lly only the displ~rPmPnt solvent is present during the drying process. It is to be lmt1~Pr~tQod that the low boiling point S of the displ~rPmP-nt solvent f~Cilit~tps the drying of the filter cake.
As dc~,clil)ed above, NMP is the most y~,f~lcd selective cryst~lli7~tion solvent for the pr~tire of the invention. It is non-aqueous, fh.orm~lly stable, non-toxic (~ ilu~ lly safe), non-col,osi~, and co--...-~r~ially available. NMP is the prcf~,lcd selective cryst~lli7~tion solvent for the practice of the present 10 ..,~io~, bec~llcP, among other things, its solubility versus ~ pe~n~ c curve for terepht_alic acid slo~es upwardly and to the right, which means that t~ hLllalicacid can be dissolved in it at elevated Ir~ es, and p-~c;~ ed or cryst~lli7f~d from it at lower Ir~ .,;,. However, the solubility versus t~ ldLu~t cuNe forterephthalic acid is of a much milder slope than the solubility cuNes in NMP for15 other m~teri~lC sought to be s~m~o~r~ from crude terephthalic acid, such as benzoic acid, 4~bu~ nl~l~yde (4-CBA), and p-toluic acid. As a co~e~lucllce, when crude tel~ll.~lir acid, cont~inin~ or associa~d with unreacted startin~g m~trri~lc, solvents (if any), and plOlUCl:i of side re~tion~, such as those m~ntionr~l above, or other undesired m~tPri~lc, is dissolved in NMP at an elevated lellll~Cldlu~, 20 ~ y all the m~t~ori~lc are dissolved or at least highly r~ cl~e(l. Then upon removal of heat and cooling of the NMP soh~tion of such dissolved m~teri~l.c, the pure terephth~lir acid plef,l. ~lially CNst~lli7Ps out, while the other more soluble m~teri~lc which may be .~,~.lcd as ;~ s for the present purposes remain in solution in NMP. A sep~ration is thus effected bcl~ purified terephthalic acid 25 and its ~C~oc~ d ;~..p~;l;es. NMP may be stripped of the i,--~-ilies in a lcc1~;"-;"~ column and recycled into the process, while the i~u-ilies may be recycled to the oxirli7~r step or olL~ c dis~osed of.
From the fu~oillg, it can be seen that in acco-~ ce with one aspect of the present invention, a method is provided for pro~ rin~ pl~rifiP~l terephth~lir acid 30 from crude t~.~.~lh~lir acid in which the crude tel~?l.lh~lic acid is dissolved in a desired cryst~lli7~tion solvent at an elevated ~ to form a solution and -CA 0222408l l997-l2-08 further, in which a l,ulirled tClc~hllizilic acid is crystz~lli7~d from that solution at a reduced tc.ll~cldLulc.
In acccldal~ with another aspect of the invention, a method and a~alatus are provided for ~uliryillg crude terephthz~lir acid from a liquid dispersion thereof 5 also cu,.li.i..i..g unreacted starting mz.trriz.l~, solvents, products of side rez~rtion~, and/or other ul~h~,d mz.t~riz~l~ in which the crude ~~ hll.~lir acid is filtered from that n~i~r~ion to partially sepz~. ale it from the other materials contained therein by filtration to produce a crude ~~ hlhz~lir acid filter cake, and then dissolving that filter cake in a desired selective crystz~lli7z~tio} solvent at an elevated t~ dl...c to form a solution. Purified terephthz~lir, acid is crystz~lli7~d from that solution by reducing the If ..l,~-dt-.lre thereof and is s~ala~cd from the solvent followingcrystz.lli7~.tion In accoldd.-ce with still another aspect of the invention, a method and a~palaLus are provided for producing purified terephthz.lic acid from crude 15 terephthalic acid by dissolving the crude tcrephll.,.lir acid in a desired selective crystz~lli7z~ti~n solvent at an Cl.,vaLcd t~ f ~l---c to form a first solution. First stage purified ltlc~hLLalic acid is crystz-lli7~d from that first solution at a reduced '...e. I'he first stage pllrifi~d terephthalic acid is se~alàLed from the solvent solution of other i~ ulilies and redissolved in the desired selective crystz.lli7z.tion 20 solvent at an elevated Iclll~."alwc to form a second solution. This second solution is cryst~lli7rA at a reduced trmrrrat~lre to for n a second stage purified terephthz,lir acid and the second stage purified lclc~;ll.~lir, acid is ~_~alaLed from the second solution.
In accoldallcc with yet another aspect of the invention, crude terephthalic 25 acid is synth~o~i7~d by contzlrting paraxylene with oxygen in an oxidi_er reaction.
The crude terephthz~lir acid is withdrawn from the oxidi_er and seL,aldlcd grossly from the side products of the reaction, and unreacted starting mztrriz~l~ The separated crude lc~h~ lir acid is then dissolved in a desired selective crys~lli7~tit~n solvent at an elevated lclll~elalule and cryst~lli7ed from it as purified 30 t~hfh~lir acid at a reduced l~ )c~alwc. More than one stage of dissolving in a desired sclc~;livc cry.st~lli7~tion solvent at an cl~,val~d ~ ...t followed by W O 96/40612 PCT~U~ S~15 crystAlli7~tion at a reduced 1' ~ C;t with accol~dllyillg separation and washing of the cryst~lli7~ purified ~,~hll.~lir acid, may be ~.,Lr~,lmed.
~ From the r lCgOillg, it can be seen that an object of the present invention to provide an il~ vcd method and a~alatus for producing purified ~rt,~h~ lir acid S of a purity desired for use in f~ g polyester resin and other products, at an -";~ ly aLLld~;livc rate, and at OlJelalillg cQr~Aition~ of reduced S~ ,iLy which require a lower capitdl i l~ LIt and simplified yr~ces~illg. The manner in whichthese and other objects of the i lve~l~ll are attained may be learned by co~ eration of the det,i~ de..~ ion of the invention which follows, together with the 10 ~CCol..~ yi~g dl~wi~g~.
BRIEF DESCRIPI ION OF I~IE DRAVVINGS
A more complete l~n~ uliuf~ of the method and a~dldlus of the present ,n may be ollt~i,led by l~fe..,.lce to the following Detailed Description when 15 taken in cQl.j.~ l;on with the accom~-ying Dl~whlgs wl.~,c ,1:
PIGS. lA and lB are simplified flow diagrams of an a~dlalus with which the method according to the invention may be practiced wlltlcllLFIG~ lA is that portion of the a~dlalUS for pc~Çc"l.Piug the first stage crystAlli7~tiQn steps and wLelein FIG. lB is that portion of the a~ .lus for pclr(.lll.i-.g the second stage 20 cryst~lli7~ti~-n steps; and FIG. 2 is a plot of solubility versus t~ ,ldlul~i curves for ~,hlLalic acid and for hll~ulilies or side reaction products commonly ~oci~te~i with crude tere~hth~lir acid.
DETAILED DESCRIPTION OF EMBODIMENTS
nPc~
The present invention relates to the development of a new PTA
".~..,.r~ ",;,~ t~hnology. Colll~alcd to the current widely used PTA technology,this technology provides a ~I,sli~ y lower capital hl~lcsL~cnl in new PTA plant 30 co~llu.;lion, as well as lower costs of plant C~lldtiOIl. It also provides means for W 096/40612 PCTA~ 9015 current DMT plants to co-~luce PTA, to sl~ their co.. l.eiil i ~c~ess against newer PTA plants.
Process S.. ~, y The success of this process is based on the development of a low ~ ,Swc, low l~ll~ClaLul~, non-aqueous, highly sel~;livc crystAlli7Ation technology. The cryst~lli7Ation ~'h~-hlhyy can purify the crude tcL~lJt-.lt.Alir acid (TA) with purity as low as from ~ ,. ~n about 70% (from the oxi~ii7~or) and about 98 + % in the first-stage crystallizer, and about 99.99+ % in the second-stage crystallizer. This allows the TA ~xi(1j7~r to be O~llatcd at much lower s~ ily than those of widely used prior art ~uc~s. No acetic acid (as solvent/diluent) or l,lo~h¢-catalyst illiLialo~
is needed in the oxi~li7~r in acccl~ ce with the present invention. The selective cryst~lli7Ation solvent used in the cryst~lli7~tion process is non-aqueous, thP~ lly stable, non-toxic (e~lvi~u~ lly safe), non~,,usivc~ and co~ ;ially available.
When c~lyil-g out the method accc,~ g to the present invention with the apparatus shown in FIGS. lA and lB, c~ layillg NMP as the selective cryst~lli7~tion solvent, the present inventors have d~ I n~ aled TPA purity levels of up to 99.9+wt%
after a first cry.ct~lli7~tion process, and up to 99.99+wt% after a second cry.st~lli7~ti~ n process. In ~ liculdl~ Table 1 illustrates the recovery of 99.95wt% pure TPA after the first cryst~lli7-~tiQn process and 99.997wt% pure TPA after the second cry~t~lli7~tinn process, from crude TPA (89.89wt% TPA).
-W O96/40612 PCTrU~C~S01 TARTF l 1st Cry.~t~11i7~tion ~nf1C~i.ll.,i1l;l.
S
(a) Weight of TPA: 56.34 grams 31.81 grams (b) Weight of Cryst~lli7~tiQn Solvent: 400.02 grams 248.38 grams (c) Saturation Te.~ lule: 60~C
(d) Cryst~lli7~tiorl Tell~p~,laLIlre: 15~C (one hour) (1) Crude TPA Product Composition:
Benzoic p-Toluic 4-CBA TPA Others 0.39wt% 4.49wt% 2.49WT% 89.89WT% 2.74VVI%
(2) First Cryst~lli7~tiorl Product 35ppm 143ppm 359ppm 99.9~wt% Not Detected (3) Second Cryst~lli7~tion Product <20ppm <20ppm <lOppm 99.997+wt%
WO 96/40612 PCT~US96/0901 Table 2 illustrates the recovery of 99.90wt% pure TPA after the first cryst~ 7~tiQn process and 99.9933wt% pure TPA after the second cryst~lli7~tinn process from crude TPA (89.89wt% TPA) by increasing both the saturation t~ Lu~e and the cryst~lli7~tion te.llpel~Lule.
T~RT F. ?
1 st Cryst~11i7~tion ~n~
~a) Weight of TPA: 138.08 grams 70.15 grams (b) Weight of Cryst~11i7~tion Solvent: 685.30 grams 247.46 grams (c) SaturationT~.n.~e ~LUI~ 110~C 105~C
(d) Cryst~lli7~tion Tt~ lule: 40~C 40~C
(1) Crude TPA Product Composition:
Rçn7.oic p-Toluic 4-CBA TPA Others 0.39wt% 4.49wt% 2.49wt% 89.89wt% 2.74wt%
(2) First Cryst~lli7~tioîl Product (Recovery: 56.5wt%) Benzoic p-Toluic 4-CBA TPA Others 28ppm 367ppm 390ppm 99.90wt% 229ppm (3) Second Cryst~lli7~tion Product (Recovery: 47.5 wt%) ClOppm <19ppm 25ppm 99.9933wt% 13ppm W O 96/40612 PCTrUS9G/09015 Table 3 illu~ tes the recovely of 99.9960wt% pure PTA (single cryst~lli7~tinn process) ~om crude TPA (98.99wt% TPA). ~ addition, each of benzoic, p-Toluic, 4-CBA, MMT and other impurities were at less than 1 Oppm.
TABT F.3 (a) Weight of TPA: 152.67 grams (b) Weight of Cryst~lli7~tion Solvent: 786.19 grams (c) Saturation Te.lll.el~ re: 100~C
(d) Cry.stsllli7~ltio~ Te.ll~J~laLulG: 40~C
(1) Crude TPAProduct Co~ o~;l;Qn Rçn7Qic p-Toluic 4-CBA TPA MMT Others <lOpprr~ ~lOppm 18ppm 98.99wt% 303ppm 0.98wt%
(2) Cryst~lli7~tiQn Product (Recovery: 50.2 wt%) <lOppm ~lOppm ClOppm >99.9960wt% <lOppm <lOppm W O 96/40612 PCT/~'~sl~cls Table 4 illustrates the recove~ of 99.63wt% pure TPA (single c~yst~lli7~tior~
process) from crude TPA (83.91wt% TPA) on a large scale basis.
T~RT.F 4 (a) Weight of TPA: 1760 grams (b) Weight of Cryst~lli7~tion Solvent: 6162 grams (c) Saturation Te.llpel~lule: 160~C
(d) Cryst~lli7~tiorl Te,ll~GI~Lule: 50~C
(1) Crude TPA Feed Product Composition:
Rf~n7.oic p-Toluic 4-CBA TPA Others 1.03wt% 4.79wt% 5.03wt% 83.91wt% 5.24wt%
(2) Cryst~11i7~tion Product (Recovery: 24.3wt%) 38ppm 852ppm 0.23wt% 99.63wt% 500ppm CA 0222408l l997-l2-08 W O 96/40612 PCT/~ 0~0lS
Table S illustrates the recovery of 99.92wt% pure TPA (single cryst~lli7~tinn process) from crude TPA (79.79wt% TPA) on a large scale basis.
TAT~T F. s (a)Weight of TPA: 1700 grams (b) Weight of Cryst~11i7~tion Solvent: 5928 grams (c) Saturation T~,.. l~e-~ re: 160~C
(d) Cryst~ 7~tic~n T~ re: 45~C
(1) Crude TPA Feed Product Composition:
Benzoic p-Toluic 4-CBA TPA Others 1.59wt% 5.19wt% 7.61wt% 79.79wt% 5.81wt%
(2) Cryst~ 7~tion Product (Recovery: 31.5wt%) 10ppm 203ppm 446ppm 99.92wt% 184ppm W O96t40612 PCTAUS96/09015 Table 6 illu~L-~es the rec~vcl~ of 99.15~,-vt% pure TPA (single cryst~ tion process) from crude TPA (83.90wt% TPA) on a large scale basis at a higher saturation temperature of 190~C.
S T.ART P 6 (a)Weight of TPA: 1965 grams (b) Weight of Cly.st~lli7~tion Solvent: 5684 grams io (c)Saturation T~ Lule: 190~C
(d)Cryst~lli7~tion Te.llpe.aLule 40~C
(1) Crude TPA Feed Product Composition:
n~ ;c p-Toluic 4-CBA TPA Others 1.23wt% 5.25wt% 6.34wt% 83.90wt% 3.28wt%
(2) Cryst~lli7~tiQn Product (Recovcly. 48.9wt%) _ O.14~,-vt% 0.61wt% 99.15~-vt% 0. l~-vt%
=
c W O96t40612 PCTAUS9~/0~015 Table 7 illu~lla~es the ~ y of 99.9915wt% pure TPA from crude TPA
(98.50wt% TPA) on a large scale basis. The ~upe.~Lul~Lion of the cryst~lli7~tion mi~ure resulted in the r.,, ~ n of ~ .I;AIIY larger TPA crystals than those crystals reSultin~ from the processes su~ ed above. As would be understood by one S sl~lled in the art, the sizes of TPA crystals are an ;lllL,ol l~lL con~ ration with respect to separation thereof from solvents and illlpuliLies T~RT.F 7 (a) WeightofTPA: 2333 grams (b) Weight of Cryst~11i7~tion Solvent: 5698 grams (c) Saturation Tclly~t laLu.c;:160~C
(d) Cryst~lli7~tion T~ claLule:45~C
1~ .
(1) Crude TPA Feed Product Coll.po~iLion:
3e~ ic p-Toluic 4-CBA TPA Others 198ppm 0.15wt% 1.23wt% 98.50wt% 989ppm (2) Cryst~lli7~tio~ Product (Recovery: 69.7wt%) < 10ppm 26ppm 38ppm 99.9915wt% 11ppm WO 96/4061t PCT~US96/09015 ACCO~ g to the invention and as can be seen in the process flow diagrams of FIGS. lA and lB, a ple~il~l embo lim~nt of the process is divided into five s~l;o (1) Oxidation Section:
In this section, p-xylene is oxitli7~d accordillg to the following main reactions:
(a) p-xylene + oxygen > terephth~lir acid (b) p-xylene + oxygen- > p-toluic acid (c) p-xylene + oxygen > 4-carbuAybc~ ldehyde (4-CBA) 10 The oAidi~ r~re time is a~lvx;...-~t~ ly five hours. Since the o~ i7Pr effluent will contain up to abcmt 30% TA, mixing in the oxi-li7rr is very m~ulL~L in order to ...~;..I;.;.. the yield and selectivity, and to prevent fouling and blockages. The initial mixing of tne feed streams may be achie~.,d in a static mixer (outside of the ~xirli7~r). ~urther mixing may be provided by an air sparger and by ~xtrrn~l circulation. D~el1dillg on the thorollghn~ss of the p-xylene washing step at thefilter (~ligc~lcsed below), the ~~ lir acid (TA) in the solid can vary from b~lwccn about 55% and about 90+ % .
(2) C~ li7st;( n ,cie~tinn (A) First Cryst~lli7~ti- n After filtration, the solids from the oxi~1i7Pr effluent are mixed with the mother liquor and the solvent wash liquid from the second-stage crystallizer and with a~ ition~l cryst~lli7~tiQn solvent. The mixed slurry is dissolved in a slurry tank at a pred~ ~3 t~ .e, ~lcr_lably at from b~ ,.l about 140~C and about 190~C. The saLulated solution is !-~ r . cd to a holding tank to remove p-xylenethrough eva~olalion. The sdLuldlcd solution is then fed to the first-stage batchcryst~lli7~or to recover purified TA. After the crystRl1i7~tion step, the crystallizer content is then dropped to a product holding tank and is pllmpe~1 contimloll~ly to a filter (or centrif~lge) to collect the solids to be ~~ i7Pd in the second-stage crystallizer for further ~!ll;r~r~lion r WO 96/40612 PCTAUS96/09015 (B) Second Cryst~lli7~tinIl The solids gc~ from the first crystallizer filter are redissolved in a feed dissolver with the cryst~lli7~tion solvent for the second-stage crystalli_er at a "~ crn-litinn, such as at a ~ w ~ ---c of from ~L-.~e.l about 140~C and 5 about 190~C. The ~tllrat~(1 solution is pllmpe~l to the second-stage crystalli_er for crystal growth and recovery. Then, the crystallizer content is dropped to a holding tank for final filtration and drying steps. In the filtration step, the solid (cake) is first washed by the cryst~lli7-tinn solvent to displace mother liquor ~ i..i.-p in the cake. The solid is then washed by a low-boiling solvent to displace the 10 cryst-lli7~ tion solvent in the cake. The wet cake is sent to the dryer to remove the final liquid from the PTA product.
(3) l~othPr Liquor/Solvent Rec~ tinn The mother liquor from the first crystallizer filter is l.~r~ d to a solvent 1CCOVe.~ column to recover the cryst-lli7i tion solvent from the column overhead.
15 The il-.-li~s, such as, but not int~n~l~od to be limited to, p-toluic acid, benzoic acid, 4~1~yl~-.~ ~yde (~CBA), and the like, are ,cco~cl~d from the bottom of the column. In order to make sure the column bottom slurry can be ~ r~ d back to the oX~ 7~r~ a high-boiling diluent is preferably added to the reboiler.II. Detailed Process DPS~;~IiO1. and FY~P1P
The process flow ~ -~ Tn of FIGS. lA and lB will be ~leserihed in terms of the procl~e-tinn and l~vcl~ of 65 kilograms per hour of terephth-lic acid (TA) from the air nxitlAtinn of p-xylene in the p.~c of a solution of co...l~on.,.,~ of catalysis in di..~ ,,Jhll.-l~t~ (DMT) or in a benzoic acid-water solvent system. The o~.ili~c~ t~ "~ c is ~-ef, al)ly bcL~,. ~n about from 150~C and about 250~C and 25 the pl. ~ is from ~t~.,.,n about 5 and about 10 kg per cm2. Since the oxidizer effluent will contain up to 30% TA, mixing in the oxi-li7Pr is very ~olL~ in order to ~)-~ the yield and sel~A~cliviLy~ and to prevent fouling and blockages.The initial mixing of the feed streams may be achieved in a static mixer (outs,ide of the oXi~li7~r)~ Further mixing may be provided by air ~.aLgillg and external ~l~Atir)n In the ~ f~ d form of the process about 0.001 - 0.05 kg per hour of ...~n~ se acetate and about 0.003 - 0.010 kg per hour of cobalt acetate in aqueous solution are fed to the oxidizer to catalyze the oxi~l~tion re~rti~nc.
The effluent from the oxi~li7~or (483.7 kg/hr) at about 160~C is llal~r~ ,d through line 1 to filter F-l to .c~ the solid from mother liquor (filtrate). In 5 filter F-1, the solid cake is washed with 250.0 kg per hour of p-xylene which is heated by heater E-l from 30 to 100-150~C. The mother liquor (281.4 kg/hr) from filter F-l is L.a~Ç~,.-,d via line 3 to tank T-l. The cake washing liquid from filter F-1 (306.9 kg/hr) is removed se~ ~ly from the filter through line 4 to tank T-2.- The washed cake from filter F-1 is dropped into a slurry tank T-3 through 10 line 8 to mix with the following streams:
Stream 19: 67.9 Kg per hour of NMP (selective cryst~lli7~tion solvent) wash liquor from filter F-3 (heated from 45 to 100-150~C by Heater E-5) Stream 9: 329.3 Kg per hour of mother liquor from tank T-17 (heated from 50 to 100-150~C by heater E-2) Stream 37: 43.5 Kg per hour of NMP from tank T-l9 (heated from 45 to 100-150~C by heater ~4) The above mixture (586.1 kg/hr) from tank T-3 is then I ~ rf ~ l ~d from the bottom of the tank through line 10 to dissolver T~. The content in tank T-4 is heated indirectly from 100-150~C to 140-190~C by a hot oil heating coil in the tank.
About 75% of the p-xylene (32.8 kg/hr) and 100% of the sparging nitrogen (10 kg/hr) in the ~ ule is vaporized from the dissolver and is removed through line 11. Sparging l il.ogen is added to tank T-4 via line 47 to assist the removal of p-xylene. Vapor Streams 11 and 13 are combined into stream 5 (51.6 kg/hr), con~en.cP(l by cooler E-3, and sent to PX Storage tank T-S. The bottom effluent fromdissolverT 4 is l.al.~r~.~tocrudecrystallizerS-l ~ak;hwise.
The batch content in crude crystallizer S-l is cooled from 140-190~C to 10-20~C by an extPrn~l cooler E-6, to ~,~n~le the desired ~cuper-saturation for TA
crystals to grow. To i~ n~ the crystal size ~ ;on and solid reco~e.y, crystal seeding may be helpful. At the c~ (l.. of a batch cryst~lli7~tiQn cycle, the slurry is dropped into tank T-6 and ~ r Icd to filter F-2 cc~ntiml~llcly at a rate of 544.6 kg per hour through line lS.
-W O 96/40612 PCT/U~ 3015 At filter P-2, 42.7 kg per hour of NMP (from line 38) is used to wash the cake. The mother liquor plus NMP wash are co~ ~ into stream 16 (432.6 kg/hr) to be fed to the NMP recovery colD D-l. The washed cake (154.7 kg/hr) is dropped into dissolver tank T-8 where it is mL~ed with 241.3 kg per hour of NMP
to form the super-s~ .nt~d feed for pure cryst~lli7~or S-2. NMP is heated from 45~C to 140-190~C by heater E-7 and is fed to tank T-8 through line 18.
The content of tank T-8 is ~ r~ d bal~wise to pure crystallizer S-2 where the ~~ aLul~ is cooled from 140-190~C to 30-60~C to induce TA crystal growth. The cooling is provided by circ~ tin~ the crystallizer content through an 0 extern~l Cooler E-8. Again, to ~ , the crystal si_e di~llil,ulion and crystal y, crystal seeding may be helpful. At the end of the batch cycle, the slurry is d~ ed from crystallizer S-2 into tank T-10 (feed tank for Filter F-3).
The slurry is fed to filter F-3 crlntim~ollcly through line 22 at a rate of 395.9 kg per hour. The mother liquor from the filter (301.8 kg/hr) is ~al~r~ d to tank T-17 via line 23. The cake is initially washed with NMP at 45~C to displacethe ~ g mother liquor from the cake, and then the cake is washed with the low-boiling ~ solvent, such as ~~ 1, to displace NMP from the cake.
From T-l9, the NMP wash is added through line 24 and, from T-18, the displ~c~em.ont solvent is added through line 25 to F-3 (both at a rate of 64 kg/hr).
The NMP wash liquid (67.9 kg/hr) is sent to tank T-3 (F-l slurry tank) through line 19, while the ~ Jl~r~ 1 solvent (64.1 kg/hr) is ~ L- . ~,d to tank T-13 through line 26.
The washed cake from filter F-3 (90.2 kg/hr) is dluwed through line 27 to product dryer DR-l where displ~ren~nt solvent in the cake is removed by heating and purging with a counter current flow of heated nitrogen. The dried PTA produc~
(65.2 kg/hr) is ~ d from the dryer via line 28 and is stored in the product bin.DisplAr~ solvent, f,-l~ -t ~1 with nitrogen (76.4 kg/hr) from product dryer DR-l, is vented from the dryer through line 29 to colld~ sel T-15 where the gas mixture is cooled to 25-45~C by cirC~ ting through the cooler E-12. The ~oA~ ~ di~!~ e-~ solvent (21.2 kg/hr) is ~ L. .~d to displ~re~ .l solvent tank T-18, while the non-cnn~l~n~in~ gas (55.2 kg/hr) is exited from T-15 via line 30 W O96/40612 PCT~US96/0901 to vent pot T-16. A~.o~ ately 2.4 kg per hour of NMP is fed to vent pot T-16 via line 39 to trap ~ pl~r~ r-~ solvent in stream 30 (3.8 kg/hr). The trapped G..,.-~11 solvent, plus NMP (6.1 kg/kr), is l.,...~f~ .cd to tank T-13 through line 33. Nitrogen .~ ovcd from T-16 (51.4 kg/hr) is sent back to the dryer by a blower through line 32 and Ll~uu~,h heater E-11 (to heat the stream from 25~C to 80-120~C) The bottom stream from tank T-13 (70.2 kg/kr - mi~Lulc of NMP and displ~f m~ nf solvent) is lla~rc,~l~fd through line 34 and heater E-9 (to heat the stream from 25~C to 80-120~C) to fli~l~rf.". ..l solvent evaporator T-14. The ,~ f .l-~ .. 1 solvent vapor from the O~L~àd of T-14 (42.7 kg/hr) is co~fl .~ced by co~ ~.~, E-10 and sent to ~l;~l~rc ~ 1 solvent tank T-18 via line 35. The bottomstream from T-14 (27.5 kgthr) is split into two streams: stream 39 (2.4 kg/hr) to vent pot T-16; and stream 40 (25.1 kg/hr) to filter F-3 mother liquor tank T-17.The mother liquor and NMP wash from filter F-2 are l . ~ r. . . cd to tank T-7 through line 16 and then are fed to the NMP lcco~ y column D-l. This stream (432.6 kg/hr) is heated from 15-25~C to 130-170~C by heater E-13 before ~
column D-1. The ~ ad vapor (433.3 kg/hr) is co~ n~ed through condenser E-15 and sent to con~1~n~t~ Pot T-20 via line 41. A part of the confl~n~
(39.4 kg/hr) at 160-220~C is letull.cd to the column as the reflux through line 42.
The rest of the ovclL~dd product from column D-1 (393.9 kg/hr) is sent to the NMP
check tank T-21 via line 43. From tank T-21, the ~ge.. ldl~d NMP is ~umped to the NMP storage tank T-19.
In order to make sure the slurry in Column D-1 Reboiler can be I .2, . .~r~. . cd back to the o~ " 20 to 60 kg per hour of high-boiling diluent, such as benzoic 2~ acid or DMT, is added to the reboiler through line 45. The slurry plus the high-boiling diluent (78.8 kg/hr) is willldldw-l from the bottom of column D-1 and is sent back to the o~ifli7~r through line 49.
~lthf)llph a plcr~,,l~l ~llll~liulcllL of the method and a~a~us of the present invention has been illllstr~ted in the acc.,~yhlg Dldw~ and ~lf scribed in the Çolcgoiug Detailed De~ l;f-~-, it will be ~--u1 ~~lood that the invention is not limited to the emhoflimf nt fli~c~lose~l but is capable of llUlllClUUS re~
wo 96/40612 PCT/US~5'~5015 mrrlifir~tinn~ and ~..l.,,l;l..lion~ without d~Lillg from the spiAt of the invention as set for~ and de~med by the following claims.
WO 96/40612 PCT~US96/0901 Table 2 illustrates the recovery of 99.90wt% pure TPA after the first cryst~ 7~tiQn process and 99.9933wt% pure TPA after the second cryst~lli7~tinn process from crude TPA (89.89wt% TPA) by increasing both the saturation t~ Lu~e and the cryst~lli7~tion te.llpel~Lule.
T~RT F. ?
1 st Cryst~11i7~tion ~n~
~a) Weight of TPA: 138.08 grams 70.15 grams (b) Weight of Cryst~11i7~tion Solvent: 685.30 grams 247.46 grams (c) SaturationT~.n.~e ~LUI~ 110~C 105~C
(d) Cryst~lli7~tion Tt~ lule: 40~C 40~C
(1) Crude TPA Product Composition:
Rçn7.oic p-Toluic 4-CBA TPA Others 0.39wt% 4.49wt% 2.49wt% 89.89wt% 2.74wt%
(2) First Cryst~lli7~tioîl Product (Recovery: 56.5wt%) Benzoic p-Toluic 4-CBA TPA Others 28ppm 367ppm 390ppm 99.90wt% 229ppm (3) Second Cryst~lli7~tion Product (Recovery: 47.5 wt%) ClOppm <19ppm 25ppm 99.9933wt% 13ppm W O 96/40612 PCTrUS9G/09015 Table 3 illu~ tes the recovely of 99.9960wt% pure PTA (single cryst~lli7~tinn process) ~om crude TPA (98.99wt% TPA). ~ addition, each of benzoic, p-Toluic, 4-CBA, MMT and other impurities were at less than 1 Oppm.
TABT F.3 (a) Weight of TPA: 152.67 grams (b) Weight of Cryst~lli7~tion Solvent: 786.19 grams (c) Saturation Te.lll.el~ re: 100~C
(d) Cry.stsllli7~ltio~ Te.ll~J~laLulG: 40~C
(1) Crude TPAProduct Co~ o~;l;Qn Rçn7Qic p-Toluic 4-CBA TPA MMT Others <lOpprr~ ~lOppm 18ppm 98.99wt% 303ppm 0.98wt%
(2) Cryst~lli7~tiQn Product (Recovery: 50.2 wt%) <lOppm ~lOppm ClOppm >99.9960wt% <lOppm <lOppm W O 96/40612 PCT/~'~sl~cls Table 4 illustrates the recove~ of 99.63wt% pure TPA (single c~yst~lli7~tior~
process) from crude TPA (83.91wt% TPA) on a large scale basis.
T~RT.F 4 (a) Weight of TPA: 1760 grams (b) Weight of Cryst~lli7~tion Solvent: 6162 grams (c) Saturation Te.llpel~lule: 160~C
(d) Cryst~lli7~tiorl Te,ll~GI~Lule: 50~C
(1) Crude TPA Feed Product Composition:
Rf~n7.oic p-Toluic 4-CBA TPA Others 1.03wt% 4.79wt% 5.03wt% 83.91wt% 5.24wt%
(2) Cryst~11i7~tion Product (Recovery: 24.3wt%) 38ppm 852ppm 0.23wt% 99.63wt% 500ppm CA 0222408l l997-l2-08 W O 96/40612 PCT/~ 0~0lS
Table S illustrates the recovery of 99.92wt% pure TPA (single cryst~lli7~tinn process) from crude TPA (79.79wt% TPA) on a large scale basis.
TAT~T F. s (a)Weight of TPA: 1700 grams (b) Weight of Cryst~11i7~tion Solvent: 5928 grams (c) Saturation T~,.. l~e-~ re: 160~C
(d) Cryst~ 7~tic~n T~ re: 45~C
(1) Crude TPA Feed Product Composition:
Benzoic p-Toluic 4-CBA TPA Others 1.59wt% 5.19wt% 7.61wt% 79.79wt% 5.81wt%
(2) Cryst~ 7~tion Product (Recovery: 31.5wt%) 10ppm 203ppm 446ppm 99.92wt% 184ppm W O96t40612 PCTAUS96/09015 Table 6 illu~L-~es the rec~vcl~ of 99.15~,-vt% pure TPA (single cryst~ tion process) from crude TPA (83.90wt% TPA) on a large scale basis at a higher saturation temperature of 190~C.
S T.ART P 6 (a)Weight of TPA: 1965 grams (b) Weight of Cly.st~lli7~tion Solvent: 5684 grams io (c)Saturation T~ Lule: 190~C
(d)Cryst~lli7~tion Te.llpe.aLule 40~C
(1) Crude TPA Feed Product Composition:
n~ ;c p-Toluic 4-CBA TPA Others 1.23wt% 5.25wt% 6.34wt% 83.90wt% 3.28wt%
(2) Cryst~lli7~tiQn Product (Recovcly. 48.9wt%) _ O.14~,-vt% 0.61wt% 99.15~-vt% 0. l~-vt%
=
c W O96t40612 PCTAUS9~/0~015 Table 7 illu~lla~es the ~ y of 99.9915wt% pure TPA from crude TPA
(98.50wt% TPA) on a large scale basis. The ~upe.~Lul~Lion of the cryst~lli7~tion mi~ure resulted in the r.,, ~ n of ~ .I;AIIY larger TPA crystals than those crystals reSultin~ from the processes su~ ed above. As would be understood by one S sl~lled in the art, the sizes of TPA crystals are an ;lllL,ol l~lL con~ ration with respect to separation thereof from solvents and illlpuliLies T~RT.F 7 (a) WeightofTPA: 2333 grams (b) Weight of Cryst~11i7~tion Solvent: 5698 grams (c) Saturation Tclly~t laLu.c;:160~C
(d) Cryst~lli7~tion T~ claLule:45~C
1~ .
(1) Crude TPA Feed Product Coll.po~iLion:
3e~ ic p-Toluic 4-CBA TPA Others 198ppm 0.15wt% 1.23wt% 98.50wt% 989ppm (2) Cryst~lli7~tio~ Product (Recovery: 69.7wt%) < 10ppm 26ppm 38ppm 99.9915wt% 11ppm WO 96/4061t PCT~US96/09015 ACCO~ g to the invention and as can be seen in the process flow diagrams of FIGS. lA and lB, a ple~il~l embo lim~nt of the process is divided into five s~l;o (1) Oxidation Section:
In this section, p-xylene is oxitli7~d accordillg to the following main reactions:
(a) p-xylene + oxygen > terephth~lir acid (b) p-xylene + oxygen- > p-toluic acid (c) p-xylene + oxygen > 4-carbuAybc~ ldehyde (4-CBA) 10 The oAidi~ r~re time is a~lvx;...-~t~ ly five hours. Since the o~ i7Pr effluent will contain up to abcmt 30% TA, mixing in the oxi-li7rr is very m~ulL~L in order to ...~;..I;.;.. the yield and selectivity, and to prevent fouling and blockages. The initial mixing of tne feed streams may be achie~.,d in a static mixer (outside of the ~xirli7~r). ~urther mixing may be provided by an air sparger and by ~xtrrn~l circulation. D~el1dillg on the thorollghn~ss of the p-xylene washing step at thefilter (~ligc~lcsed below), the ~~ lir acid (TA) in the solid can vary from b~lwccn about 55% and about 90+ % .
(2) C~ li7st;( n ,cie~tinn (A) First Cryst~lli7~ti- n After filtration, the solids from the oxi~1i7Pr effluent are mixed with the mother liquor and the solvent wash liquid from the second-stage crystallizer and with a~ ition~l cryst~lli7~tiQn solvent. The mixed slurry is dissolved in a slurry tank at a pred~ ~3 t~ .e, ~lcr_lably at from b~ ,.l about 140~C and about 190~C. The saLulated solution is !-~ r . cd to a holding tank to remove p-xylenethrough eva~olalion. The sdLuldlcd solution is then fed to the first-stage batchcryst~lli7~or to recover purified TA. After the crystRl1i7~tion step, the crystallizer content is then dropped to a product holding tank and is pllmpe~1 contimloll~ly to a filter (or centrif~lge) to collect the solids to be ~~ i7Pd in the second-stage crystallizer for further ~!ll;r~r~lion r WO 96/40612 PCTAUS96/09015 (B) Second Cryst~lli7~tinIl The solids gc~ from the first crystallizer filter are redissolved in a feed dissolver with the cryst~lli7~tion solvent for the second-stage crystalli_er at a "~ crn-litinn, such as at a ~ w ~ ---c of from ~L-.~e.l about 140~C and 5 about 190~C. The ~tllrat~(1 solution is pllmpe~l to the second-stage crystalli_er for crystal growth and recovery. Then, the crystallizer content is dropped to a holding tank for final filtration and drying steps. In the filtration step, the solid (cake) is first washed by the cryst~lli7-tinn solvent to displace mother liquor ~ i..i.-p in the cake. The solid is then washed by a low-boiling solvent to displace the 10 cryst-lli7~ tion solvent in the cake. The wet cake is sent to the dryer to remove the final liquid from the PTA product.
(3) l~othPr Liquor/Solvent Rec~ tinn The mother liquor from the first crystallizer filter is l.~r~ d to a solvent 1CCOVe.~ column to recover the cryst-lli7i tion solvent from the column overhead.
15 The il-.-li~s, such as, but not int~n~l~od to be limited to, p-toluic acid, benzoic acid, 4~1~yl~-.~ ~yde (~CBA), and the like, are ,cco~cl~d from the bottom of the column. In order to make sure the column bottom slurry can be ~ r~ d back to the oX~ 7~r~ a high-boiling diluent is preferably added to the reboiler.II. Detailed Process DPS~;~IiO1. and FY~P1P
The process flow ~ -~ Tn of FIGS. lA and lB will be ~leserihed in terms of the procl~e-tinn and l~vcl~ of 65 kilograms per hour of terephth-lic acid (TA) from the air nxitlAtinn of p-xylene in the p.~c of a solution of co...l~on.,.,~ of catalysis in di..~ ,,Jhll.-l~t~ (DMT) or in a benzoic acid-water solvent system. The o~.ili~c~ t~ "~ c is ~-ef, al)ly bcL~,. ~n about from 150~C and about 250~C and 25 the pl. ~ is from ~t~.,.,n about 5 and about 10 kg per cm2. Since the oxidizer effluent will contain up to 30% TA, mixing in the oxi-li7Pr is very ~olL~ in order to ~)-~ the yield and sel~A~cliviLy~ and to prevent fouling and blockages.The initial mixing of the feed streams may be achieved in a static mixer (outs,ide of the oXi~li7~r)~ Further mixing may be provided by air ~.aLgillg and external ~l~Atir)n In the ~ f~ d form of the process about 0.001 - 0.05 kg per hour of ...~n~ se acetate and about 0.003 - 0.010 kg per hour of cobalt acetate in aqueous solution are fed to the oxidizer to catalyze the oxi~l~tion re~rti~nc.
The effluent from the oxi~li7~or (483.7 kg/hr) at about 160~C is llal~r~ ,d through line 1 to filter F-l to .c~ the solid from mother liquor (filtrate). In 5 filter F-1, the solid cake is washed with 250.0 kg per hour of p-xylene which is heated by heater E-l from 30 to 100-150~C. The mother liquor (281.4 kg/hr) from filter F-l is L.a~Ç~,.-,d via line 3 to tank T-l. The cake washing liquid from filter F-1 (306.9 kg/hr) is removed se~ ~ly from the filter through line 4 to tank T-2.- The washed cake from filter F-1 is dropped into a slurry tank T-3 through 10 line 8 to mix with the following streams:
Stream 19: 67.9 Kg per hour of NMP (selective cryst~lli7~tion solvent) wash liquor from filter F-3 (heated from 45 to 100-150~C by Heater E-5) Stream 9: 329.3 Kg per hour of mother liquor from tank T-17 (heated from 50 to 100-150~C by heater E-2) Stream 37: 43.5 Kg per hour of NMP from tank T-l9 (heated from 45 to 100-150~C by heater ~4) The above mixture (586.1 kg/hr) from tank T-3 is then I ~ rf ~ l ~d from the bottom of the tank through line 10 to dissolver T~. The content in tank T-4 is heated indirectly from 100-150~C to 140-190~C by a hot oil heating coil in the tank.
About 75% of the p-xylene (32.8 kg/hr) and 100% of the sparging nitrogen (10 kg/hr) in the ~ ule is vaporized from the dissolver and is removed through line 11. Sparging l il.ogen is added to tank T-4 via line 47 to assist the removal of p-xylene. Vapor Streams 11 and 13 are combined into stream 5 (51.6 kg/hr), con~en.cP(l by cooler E-3, and sent to PX Storage tank T-S. The bottom effluent fromdissolverT 4 is l.al.~r~.~tocrudecrystallizerS-l ~ak;hwise.
The batch content in crude crystallizer S-l is cooled from 140-190~C to 10-20~C by an extPrn~l cooler E-6, to ~,~n~le the desired ~cuper-saturation for TA
crystals to grow. To i~ n~ the crystal size ~ ;on and solid reco~e.y, crystal seeding may be helpful. At the c~ (l.. of a batch cryst~lli7~tiQn cycle, the slurry is dropped into tank T-6 and ~ r Icd to filter F-2 cc~ntiml~llcly at a rate of 544.6 kg per hour through line lS.
-W O 96/40612 PCT/U~ 3015 At filter P-2, 42.7 kg per hour of NMP (from line 38) is used to wash the cake. The mother liquor plus NMP wash are co~ ~ into stream 16 (432.6 kg/hr) to be fed to the NMP recovery colD D-l. The washed cake (154.7 kg/hr) is dropped into dissolver tank T-8 where it is mL~ed with 241.3 kg per hour of NMP
to form the super-s~ .nt~d feed for pure cryst~lli7~or S-2. NMP is heated from 45~C to 140-190~C by heater E-7 and is fed to tank T-8 through line 18.
The content of tank T-8 is ~ r~ d bal~wise to pure crystallizer S-2 where the ~~ aLul~ is cooled from 140-190~C to 30-60~C to induce TA crystal growth. The cooling is provided by circ~ tin~ the crystallizer content through an 0 extern~l Cooler E-8. Again, to ~ , the crystal si_e di~llil,ulion and crystal y, crystal seeding may be helpful. At the end of the batch cycle, the slurry is d~ ed from crystallizer S-2 into tank T-10 (feed tank for Filter F-3).
The slurry is fed to filter F-3 crlntim~ollcly through line 22 at a rate of 395.9 kg per hour. The mother liquor from the filter (301.8 kg/hr) is ~al~r~ d to tank T-17 via line 23. The cake is initially washed with NMP at 45~C to displacethe ~ g mother liquor from the cake, and then the cake is washed with the low-boiling ~ solvent, such as ~~ 1, to displace NMP from the cake.
From T-l9, the NMP wash is added through line 24 and, from T-18, the displ~c~em.ont solvent is added through line 25 to F-3 (both at a rate of 64 kg/hr).
The NMP wash liquid (67.9 kg/hr) is sent to tank T-3 (F-l slurry tank) through line 19, while the ~ Jl~r~ 1 solvent (64.1 kg/hr) is ~ L- . ~,d to tank T-13 through line 26.
The washed cake from filter F-3 (90.2 kg/hr) is dluwed through line 27 to product dryer DR-l where displ~ren~nt solvent in the cake is removed by heating and purging with a counter current flow of heated nitrogen. The dried PTA produc~
(65.2 kg/hr) is ~ d from the dryer via line 28 and is stored in the product bin.DisplAr~ solvent, f,-l~ -t ~1 with nitrogen (76.4 kg/hr) from product dryer DR-l, is vented from the dryer through line 29 to colld~ sel T-15 where the gas mixture is cooled to 25-45~C by cirC~ ting through the cooler E-12. The ~oA~ ~ di~!~ e-~ solvent (21.2 kg/hr) is ~ L. .~d to displ~re~ .l solvent tank T-18, while the non-cnn~l~n~in~ gas (55.2 kg/hr) is exited from T-15 via line 30 W O96/40612 PCT~US96/0901 to vent pot T-16. A~.o~ ately 2.4 kg per hour of NMP is fed to vent pot T-16 via line 39 to trap ~ pl~r~ r-~ solvent in stream 30 (3.8 kg/hr). The trapped G..,.-~11 solvent, plus NMP (6.1 kg/kr), is l.,...~f~ .cd to tank T-13 through line 33. Nitrogen .~ ovcd from T-16 (51.4 kg/hr) is sent back to the dryer by a blower through line 32 and Ll~uu~,h heater E-11 (to heat the stream from 25~C to 80-120~C) The bottom stream from tank T-13 (70.2 kg/kr - mi~Lulc of NMP and displ~f m~ nf solvent) is lla~rc,~l~fd through line 34 and heater E-9 (to heat the stream from 25~C to 80-120~C) to fli~l~rf.". ..l solvent evaporator T-14. The ,~ f .l-~ .. 1 solvent vapor from the O~L~àd of T-14 (42.7 kg/hr) is co~fl .~ced by co~ ~.~, E-10 and sent to ~l;~l~rc ~ 1 solvent tank T-18 via line 35. The bottomstream from T-14 (27.5 kgthr) is split into two streams: stream 39 (2.4 kg/hr) to vent pot T-16; and stream 40 (25.1 kg/hr) to filter F-3 mother liquor tank T-17.The mother liquor and NMP wash from filter F-2 are l . ~ r. . . cd to tank T-7 through line 16 and then are fed to the NMP lcco~ y column D-l. This stream (432.6 kg/hr) is heated from 15-25~C to 130-170~C by heater E-13 before ~
column D-1. The ~ ad vapor (433.3 kg/hr) is co~ n~ed through condenser E-15 and sent to con~1~n~t~ Pot T-20 via line 41. A part of the confl~n~
(39.4 kg/hr) at 160-220~C is letull.cd to the column as the reflux through line 42.
The rest of the ovclL~dd product from column D-1 (393.9 kg/hr) is sent to the NMP
check tank T-21 via line 43. From tank T-21, the ~ge.. ldl~d NMP is ~umped to the NMP storage tank T-19.
In order to make sure the slurry in Column D-1 Reboiler can be I .2, . .~r~. . cd back to the o~ " 20 to 60 kg per hour of high-boiling diluent, such as benzoic 2~ acid or DMT, is added to the reboiler through line 45. The slurry plus the high-boiling diluent (78.8 kg/hr) is willldldw-l from the bottom of column D-1 and is sent back to the o~ifli7~r through line 49.
~lthf)llph a plcr~,,l~l ~llll~liulcllL of the method and a~a~us of the present invention has been illllstr~ted in the acc.,~yhlg Dldw~ and ~lf scribed in the Çolcgoiug Detailed De~ l;f-~-, it will be ~--u1 ~~lood that the invention is not limited to the emhoflimf nt fli~c~lose~l but is capable of llUlllClUUS re~
wo 96/40612 PCT/US~5'~5015 mrrlifir~tinn~ and ~..l.,,l;l..lion~ without d~Lillg from the spiAt of the invention as set for~ and de~med by the following claims.
Claims (36)
1. A method for purifying crude terephthalic acid from a liquid dispersion thereof also containing impurities selected from unreacted starting materials, solvents, products of side reactions and/or undesired materials comprising:
filtering said dispersion to form a crude terephthalic acid filter cake;
dissolving said filter cake in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C to form a solution;
crystallizing purified terephthalic acid from said solution in said crystallization solvent by reducing the temperature of said solution; and separating said crystallized purified terephthalic acid from said solution.
filtering said dispersion to form a crude terephthalic acid filter cake;
dissolving said filter cake in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C to form a solution;
crystallizing purified terephthalic acid from said solution in said crystallization solvent by reducing the temperature of said solution; and separating said crystallized purified terephthalic acid from said solution.
2. A method in accordance with Claim 1 in which said dispersion contains 4-carboxybenzaldehyde (4-CBA).
3. A method in accordance with Claim 1 in which the temperature of said solution is reduced to from between about 5°C and about 50°C.
4. A method in accordance with Claim 3 in which the temperature of said solution is reduced to from between about 10°C and about 20°C.
5. A method in accordance with Claim 1 in which said crystallization of purified terephthalic acid from solution in said selective crystallization solvent is repeated by redissolving said crystallization purified terephthalic acid in said selective crystallization solvent to form a redissolved solution at an elevated temperature; and crystallizing purified terephthalic acid from said redissolved solution in said selective crystallization solvent by reducing the temperature thereof.
6. A method in accordance with Claim 1 wherein said selective crystallization solvent is N-methyl pyrrolidone.
7. A method in accordance with Claim 1 wherein said selective crystallization solvent is selected from the group consisting of N-aLkyl-2-pyrrolidone, N-ethyl pyrrolidone, N-mercaptoalkyl-2-pyrrolidone, N-mercaptoethyl2-pyrrolidone, N-alkyl-2-thiopyrrolidone, N-methyl-2-thiopyrrolidone, N-hydroxyaLtcyl-2-pyrrolidone, and N-hydroxyethyl-2-pyrrolidone.
8. A method in accordance with Claim 1 wherein said selective crystallization solvent is selected from the group consisting of sulfolane, methyl sulfolane, sulfones, morpholine, N-formyl morpholine, carbitols, Cl to C12 alcohols, acetonitrile,adiponitrile,butyronitrile,ethers, amines, amides, and esters.
9. A method in accordance with Claim 1 and further comprising the step of washing said filter cake with a wash solvent selected from the group consisting of p- xylene,acetone,menthyl ketone and menthanol
10. A method in accordance with Claim 9 wherein said wash solvent is p-xylene.
11. A method in accordance with Claim 1 and further comprising the step of displacing said selective crystallization solvent subsequent to the step of crystallization with a displacement solvent selected from the group consisting of methanol, methyl ethyl ketone, and acetone.
12. A method in accordance with Claim 1 wherein said displacement solvent is methanol
13. A method for producing purified terephthalic acid from crude terrephthalic acid comprising:
dissolving crude terephthalic acid in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C to form a solution; and crystallization purified terephthalic acid from said solution at a reduced temperature
dissolving crude terephthalic acid in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C to form a solution; and crystallization purified terephthalic acid from said solution at a reduced temperature
14. A method in accordance with Claim 13 wherein said selective crystallization solvent is N-methyl pyrrolidone.
15. A method in accordance with Claim 13 and further comprising the step of separating said purified terephthalic acid from said solution.
16. A method in accordance with Claim 15 in which said step of separating is effected by filtering or centrifuging said purified terephthalic acid from said solution, washing it with said selective crystallization solvent and with adisplacement solvent, and thereafter drying it.
17. A method in accordance with Claim 13 wherein said selective crystallization solvent is selected from the group consisting of N-alkyl-2-pyrrolidone, N-ethyl pyrrolidone, N-mercatoalky-2-pyrrolidone, N-mercatoethyl 2-pyrrolidone, N-alkyl-2-thiopyrrolidone, N-methyl-2-thiopyrrolidone, N-hydroxyalkyl-2-pyrrolidone, and N-hydroxyethyl-2-pyrrolidone.
18. A method in accordance with Claim 13 wherein said selective crystallization solvent is selected from the group consisting of sulfolane, methyl sulfolane, sulfones, morpholine, N-formyl morpholine, carbitols, Cl to C12 alchols, acetonitrile, adiponitrile, butyronitrile, ethers, amines, amides, and esters.
19. A method in accordance with Claim 13 wherein said crude terephthalic acid is washed with a wash solvent selected from the group consisting of p-xylene,menthanol, acetone and methyl ethyl ketone.
20. A method in accordance with Claim 19 wherein said wash solvent is p-xylene.
21. A method in accordance with Claim 13 comprising the step of displacing said selective crystallization solvent subsequent to the step of crystallization with a displacement solvent selected from the group consisting of menthanol, methyl ethyl ketone and acetone.
22. A method in accordance with with Claim 21 wherein said displacement solvent is menthanol.
23. A method for producing purified terephthalic acid from crude terephthalic acid comprising;
dissolving crude terephthalic acid in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C to form a first solution, crystallizing first stage purified terephthalic acid from said first solution at a reduced temperature;
separating said crystallized first stage purified terephthalic acid from said solution;
redissolving said separated first stage purified terephthalic acid in said selective crystallization solvent at an elevated temperature to form a second solution;
crystallizing second stage purified terephthalic acid from said second solution at a reduced temperature; and separating said crystallized second stage purified terephthalic acid from said second solution
dissolving crude terephthalic acid in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C to form a first solution, crystallizing first stage purified terephthalic acid from said first solution at a reduced temperature;
separating said crystallized first stage purified terephthalic acid from said solution;
redissolving said separated first stage purified terephthalic acid in said selective crystallization solvent at an elevated temperature to form a second solution;
crystallizing second stage purified terephthalic acid from said second solution at a reduced temperature; and separating said crystallized second stage purified terephthalic acid from said second solution
24. A method in accordance with Claim 23 in which said step of separating is effected by filtering or centrifuging said purified terephthalic acid from said solution, washing it with said selective crystallization solvent and with adisplacement solvent, and thereafter drying it.
25. A method in accordance with Claim 23 wherein said crystallization solvent is N-methyl pyrrolidone.
26. A method in accordance with Claim 23 wherein said selective crystallization solvent is selected from the group consisting of N-alkyl-2-pyrrolidone, N-ethyl pyrrolidone, N-mercapyoalkyl-2-pyrrolidone, N-mercaptoethyl-2-pyrrolidone, N-alky1-2-thiopyrrolidone, N-methyl-2-thiopyrrolidone, N-hydroyalkyl-2-pyrrolidone, and N-hydroxyethyl-2-pyrrolidone.
27. A method in accordance with Claim 23 wherein said selective crystallization solvent is selected from the group consisting of sulfolane, methyl sulfolane, sulfones, morpholine, N-formyl morpholine, carbitols, C1 to C12 alcohols, acetonitrile, adiponitrile, butyronitrile, ethers, amines, amides, and esters.
28. A method in accordance with Claim 23 wherein said crude terephthalic acid is washed with a wash solvent selected from the group consisting of p-xylene, methanol, acetone and methyl ethyl ketone.
29. A method in accordance with Claim 28 wherein said wash solvent is p-xylene.
30. A method in accordance with Claim 23 comprising the step of displacement said selective crystallization solvent subsequent to said second stage crystallization step with a displacement solvent selected from the group consisting of methanol, methyl ethyl ketone, and acetone.
31. A method in accordance with Claim 30 wherein said displacement solvent is methanol.
32. A method for purifying crude terephthalic acid from a liquid dispersion thereof also containing impurities from unreacted starting materials, solvents, products of side reactions and/or other undesired materials, said method comprising the steps of:
dissolving crude terephthalic acid in N-methyl pyrrolidone at a temperature of from between about 140°C and about 190°C to form a first solution;
crystallization said dissolved crude terephthalic acid from said first solution at a temperature of from between about 5°C and about 50°C to form first stage purified terephthalic acid;
separating said first stage purified terephthalic acid from said first solution by filtration to form a first stage purified terephthalic acid filter cake;
washing said separated first stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
redissolving said first stage purified terephthalic acid filter cake in NMP at a temperature of from between about 140°C and about 190°C to form a second solution;
crystallizing said redissolved first stage purified terephthalic acid from said second solution at a temperature of from between about 5°C and about 50°C to form second stage purified terephthalic acid;
separating said second stage purified terephthalic acid from said second solution by filtration to form a second stage purified terephthalic acid filter cake, washing said second stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
washing said N-methyl Pyrrolidone washed filter cake with methanol; and drying said second stage purified terephthalic acid filter cake to provide second stage purified terephthalic acid.
dissolving crude terephthalic acid in N-methyl pyrrolidone at a temperature of from between about 140°C and about 190°C to form a first solution;
crystallization said dissolved crude terephthalic acid from said first solution at a temperature of from between about 5°C and about 50°C to form first stage purified terephthalic acid;
separating said first stage purified terephthalic acid from said first solution by filtration to form a first stage purified terephthalic acid filter cake;
washing said separated first stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
redissolving said first stage purified terephthalic acid filter cake in NMP at a temperature of from between about 140°C and about 190°C to form a second solution;
crystallizing said redissolved first stage purified terephthalic acid from said second solution at a temperature of from between about 5°C and about 50°C to form second stage purified terephthalic acid;
separating said second stage purified terephthalic acid from said second solution by filtration to form a second stage purified terephthalic acid filter cake, washing said second stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
washing said N-methyl Pyrrolidone washed filter cake with methanol; and drying said second stage purified terephthalic acid filter cake to provide second stage purified terephthalic acid.
33. A method of making purified terephthalic acid comprising the steps of:
contacting p-xylene with oxygen to form crude terephthalic acid in a dispersion thereof also containing impurities selected from unreacted starting materials, solvents, products of side reaction and/or other undesired materials dissolving crude terephthalic acid in N-methyl pyrrolidone at a temperature of from between about 140°C and about 190°C to form a first solution;
crystallizing said dissolved crude terephthalic acid from said first solution ata temperature of from between about 5°C and about 50°C to form first stage purified terephthalic acid;
separating said first stage purified terephthalic, acid from said first solutionby filtration to form a first stage terephthalic acid filter cake;
~ washing said separated first stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
redissolving said first stage purified terephthalic acid filter cake in N-methylpyrrolidone at a temperature of from between about 140°C and about 190°C to form a second solution;
crystallizing said redissolved first stage purified terephthalic acid from said second solution at a temperature of from between about 5°C and about 50°C to form second stage purified terephthalic acid;
separating said second stage purified terephthalic acid from said second solution by filtration to form a second stage purified terephthalic acid filter cake;
washing said second stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
washing said N-methyl pyrrolidone washed filter cake with methanol; and drying said second stage purified terephthalic acid filter cake to provide second stage purified terephthalic acid.
contacting p-xylene with oxygen to form crude terephthalic acid in a dispersion thereof also containing impurities selected from unreacted starting materials, solvents, products of side reaction and/or other undesired materials dissolving crude terephthalic acid in N-methyl pyrrolidone at a temperature of from between about 140°C and about 190°C to form a first solution;
crystallizing said dissolved crude terephthalic acid from said first solution ata temperature of from between about 5°C and about 50°C to form first stage purified terephthalic acid;
separating said first stage purified terephthalic, acid from said first solutionby filtration to form a first stage terephthalic acid filter cake;
~ washing said separated first stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
redissolving said first stage purified terephthalic acid filter cake in N-methylpyrrolidone at a temperature of from between about 140°C and about 190°C to form a second solution;
crystallizing said redissolved first stage purified terephthalic acid from said second solution at a temperature of from between about 5°C and about 50°C to form second stage purified terephthalic acid;
separating said second stage purified terephthalic acid from said second solution by filtration to form a second stage purified terephthalic acid filter cake;
washing said second stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
washing said N-methyl pyrrolidone washed filter cake with methanol; and drying said second stage purified terephthalic acid filter cake to provide second stage purified terephthalic acid.
34. An apparatus for purifying crude terephthalic acid from a liquid dispersion thereof also containing impurities selected from unreacted starting materials, solvents, products of side reaction and/or other undesired materials comprising.
means for filtering said dispersion to form a crude terephthalic acid filter cake;
means for dissolving said filter cake in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C
to form a solution;
means for crystallizing purified terephthalic acid from said solution in said crystallization solvent by reducing the temperature of said solution; and means for separating said crystallized purified terephthalic acid from said solution.
means for filtering said dispersion to form a crude terephthalic acid filter cake;
means for dissolving said filter cake in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C
to form a solution;
means for crystallizing purified terephthalic acid from said solution in said crystallization solvent by reducing the temperature of said solution; and means for separating said crystallized purified terephthalic acid from said solution.
35. An apparatus for producing purified terephthalic acid from crude terephthalic acid comprising:
means for dissolving crude terephthalic acid in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C to form a first solution;
means for crystallizing first stage purified terephthalic acid from said first solution at a reduced temperature;
means for separating said crystallized first stage purified terephthalic acid from said solution;
means for redissolving said separated first stage purified terephthalic acid in a selective crystallization solvent at an elevated temperature to form asecond solution;
means for crystallizing second stage purified terephthalic acid from said second solution at a reduced temperature; and means for separating said crystallized second stage purified terephthalic acid from said second solution.
means for dissolving crude terephthalic acid in a selective crystallization solvent at an elevated temperature of from between about 140°C and about 190°C to form a first solution;
means for crystallizing first stage purified terephthalic acid from said first solution at a reduced temperature;
means for separating said crystallized first stage purified terephthalic acid from said solution;
means for redissolving said separated first stage purified terephthalic acid in a selective crystallization solvent at an elevated temperature to form asecond solution;
means for crystallizing second stage purified terephthalic acid from said second solution at a reduced temperature; and means for separating said crystallized second stage purified terephthalic acid from said second solution.
36. An apparatus for purifying crude terephthalic acid from a liquid dispersion thereof also containing impurities selected from unreacted starting materials, solvents, products of side reactions and/or other undesired materials, said apparatus comprising:
means for dissolving crude terephthalic acid in NMP at a temperature of from between about 140°C and about 190°C to form a first solution;means for crystallizing said dissolve crude terephthalic acid from said first solution at a temperature of from between about 5°C and about 50°C to form first stage purified terephthalic acid;
means for separating said first stage purified terephthalic acid from said firstsolution by filtration to form a first stage purified terephthalic acid filter cake;
means for washing said separated first stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
means for redissolving said first stage purified terephthalic acid filter cake in NMP at a temperature of from between about 140°C and about 190°C to form a second solution;
means for crystallizing said redissolved first stage purified terephthalic acid from said second solution at a temperature of from between about 5°C and about 50°C to form second stage purified terephthalic acid;
means for separating said second stage purified terephthalic acid from said second solution by filtration to form a second stage purified terephthalic acid filter cake;
means for washing said second stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
means for washing said N-methyl Pyrrolidone washed filter cake with methanol; and means for drying said second stage purified terephthalic acid filter cake to provide second stage purified terephthalic acid.
means for dissolving crude terephthalic acid in NMP at a temperature of from between about 140°C and about 190°C to form a first solution;means for crystallizing said dissolve crude terephthalic acid from said first solution at a temperature of from between about 5°C and about 50°C to form first stage purified terephthalic acid;
means for separating said first stage purified terephthalic acid from said firstsolution by filtration to form a first stage purified terephthalic acid filter cake;
means for washing said separated first stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
means for redissolving said first stage purified terephthalic acid filter cake in NMP at a temperature of from between about 140°C and about 190°C to form a second solution;
means for crystallizing said redissolved first stage purified terephthalic acid from said second solution at a temperature of from between about 5°C and about 50°C to form second stage purified terephthalic acid;
means for separating said second stage purified terephthalic acid from said second solution by filtration to form a second stage purified terephthalic acid filter cake;
means for washing said second stage purified terephthalic acid filter cake with N-methyl pyrrolidone;
means for washing said N-methyl Pyrrolidone washed filter cake with methanol; and means for drying said second stage purified terephthalic acid filter cake to provide second stage purified terephthalic acid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/477,898 | 1995-06-07 | ||
| US08/477,898 US5767311A (en) | 1995-06-07 | 1995-06-07 | Method and apparatus for preparing purified terephtalic acid |
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| Publication Number | Publication Date |
|---|---|
| CA2224081A1 true CA2224081A1 (en) | 1996-12-19 |
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| CA002224081A Abandoned CA2224081A1 (en) | 1995-06-07 | 1996-06-06 | Method and apparatus for preparing purified terephthalic acid |
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|---|---|
| US (2) | US5767311A (en) |
| EP (1) | EP0857170B1 (en) |
| JP (2) | JP4272704B2 (en) |
| KR (1) | KR100452021B1 (en) |
| CN (1) | CN1080253C (en) |
| AR (1) | AR002370A1 (en) |
| AU (1) | AU6047296A (en) |
| BR (1) | BR9609055A (en) |
| CA (1) | CA2224081A1 (en) |
| DE (1) | DE69628319T2 (en) |
| ES (1) | ES2194105T3 (en) |
| IL (1) | IL122287A (en) |
| MY (1) | MY123045A (en) |
| RU (1) | RU2163231C2 (en) |
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-
1995
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-
1996
- 1996-05-25 TW TW085106229A patent/TW424084B/en not_active IP Right Cessation
- 1996-05-28 ZA ZA964318A patent/ZA964318B/en unknown
- 1996-05-29 MY MYPI96002045A patent/MY123045A/en unknown
- 1996-06-06 AU AU60472/96A patent/AU6047296A/en not_active Abandoned
- 1996-06-06 CN CN96195921A patent/CN1080253C/en not_active Expired - Fee Related
- 1996-06-06 WO PCT/US1996/009015 patent/WO1996040612A1/en active IP Right Grant
- 1996-06-06 CA CA002224081A patent/CA2224081A1/en not_active Abandoned
- 1996-06-06 IL IL12228796A patent/IL122287A/en not_active IP Right Cessation
- 1996-06-06 JP JP50143497A patent/JP4272704B2/en not_active Expired - Fee Related
- 1996-06-06 DE DE69628319T patent/DE69628319T2/en not_active Expired - Fee Related
- 1996-06-06 ES ES96918139T patent/ES2194105T3/en not_active Expired - Lifetime
- 1996-06-06 AR AR10300996A patent/AR002370A1/en unknown
- 1996-06-06 KR KR1019970708778A patent/KR100452021B1/en not_active IP Right Cessation
- 1996-06-06 BR BR9609055-3A patent/BR9609055A/en not_active Application Discontinuation
- 1996-06-06 EP EP96918139A patent/EP0857170B1/en not_active Expired - Lifetime
- 1996-06-06 RU RU98100263/04A patent/RU2163231C2/en not_active IP Right Cessation
-
1998
- 1998-05-07 US US09/074,251 patent/US5961935A/en not_active Expired - Lifetime
-
2008
- 2008-11-18 JP JP2008294438A patent/JP2009091359A/en active Pending
Also Published As
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|---|---|
| IL122287A (en) | 2001-05-20 |
| US5767311A (en) | 1998-06-16 |
| JP2009091359A (en) | 2009-04-30 |
| ES2194105T3 (en) | 2003-11-16 |
| ZA964318B (en) | 1996-12-06 |
| RU2163231C2 (en) | 2001-02-20 |
| DE69628319D1 (en) | 2003-06-26 |
| IL122287A0 (en) | 1998-04-05 |
| US5961935A (en) | 1999-10-05 |
| DE69628319T2 (en) | 2004-05-13 |
| MY123045A (en) | 2006-05-31 |
| TW424084B (en) | 2001-03-01 |
| EP0857170B1 (en) | 2003-05-21 |
| EP0857170A4 (en) | 1998-09-02 |
| KR19990022299A (en) | 1999-03-25 |
| JP4272704B2 (en) | 2009-06-03 |
| MX9709686A (en) | 1998-10-31 |
| AU6047296A (en) | 1996-12-30 |
| WO1996040612A1 (en) | 1996-12-19 |
| BR9609055A (en) | 1999-12-14 |
| CN1192198A (en) | 1998-09-02 |
| EP0857170A1 (en) | 1998-08-12 |
| KR100452021B1 (en) | 2005-04-06 |
| CN1080253C (en) | 2002-03-06 |
| JPH11507055A (en) | 1999-06-22 |
| AR002370A1 (en) | 1998-03-11 |
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